X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=GHC%2FRead.lhs;h=77daececb7306dfda10659d977d823f7114a3d82;hb=41e8fba828acbae1751628af50849f5352b27873;hp=b568287e66b625a72e4c09e19ebf9b4ee5d282c8;hpb=ccc7548348fa0d5a10e4c795c5edc13d0dd3f014;p=ghc-base.git

diff --git a/GHC/Read.lhs b/GHC/Read.lhs
index b568287..77daece 100644
--- a/GHC/Read.lhs
+++ b/GHC/Read.lhs
@@ -1,6 +1,7 @@
 \begin{code}
-{-# OPTIONS_GHC -XNoImplicitPrelude #-}
+{-# LANGUAGE CPP, NoImplicitPrelude #-}
 {-# OPTIONS_HADDOCK hide #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  GHC.Read
@@ -451,28 +452,28 @@ instance Read L.Lexeme where
 %*********************************************************
 
 \begin{code}
-readNumber :: Num a => (L.Lexeme -> Maybe a) -> ReadPrec a
+readNumber :: Num a => (L.Lexeme -> ReadPrec a) -> ReadPrec a
 -- Read a signed number
 readNumber convert =
   parens
   ( do x <- lexP
        case x of
-         L.Symbol "-" -> do n <- readNumber convert
+         L.Symbol "-" -> do y <- lexP
+                            n <- convert y
                             return (negate n)
-       
-         _   -> case convert x of
-                   Just n  -> return n
-                   Nothing -> pfail
+
+         _   -> convert x
   )
 
-convertInt :: Num a => L.Lexeme -> Maybe a
-convertInt (L.Int i) = Just (fromInteger i)
-convertInt _         = Nothing
 
-convertFrac :: Fractional a => L.Lexeme -> Maybe a
-convertFrac (L.Int i) = Just (fromInteger i)
-convertFrac (L.Rat r) = Just (fromRational r)
-convertFrac _         = Nothing
+convertInt :: Num a => L.Lexeme -> ReadPrec a
+convertInt (L.Int i) = return (fromInteger i)
+convertInt _         = pfail
+
+convertFrac :: Fractional a => L.Lexeme -> ReadPrec a
+convertFrac (L.Int i) = return (fromInteger i)
+convertFrac (L.Rat r) = return (fromRational r)
+convertFrac _         = pfail
 
 instance Read Int where
   readPrec     = readNumber convertInt